Mendes, 38, kicks off the four-hour series – airing Oct. 1 and 2 at 9 p.m. ET on PBS – with her visit to Sierra Leone, where she meets with activist Amie Kandeh, a survivor of gender-based violence working with the International Rescue Committee to help other survivors toward safe, productive futures.

"I knew I was in for a life-changing experience," Mendes says of participating in the project.

"This experience has profoundly affected me," she says. "I was so shocked and saddened to learn the extent of gender-based violence taking place in Sierra Leone every day and that trip has made me want to be a part of the solution."

See Mendes meet and exchange necklaces with Fulumatu, a young girl who bravely pressed charges against her rapist in the clip below.